Controlling morphology and microstructure of conjugated polymers via solution-state aggregation

The macroscopic functions and properties of conjugated polymers depend on their microcosmic morphol-ogy and microstructure in the solid state. However, such morphology and microstructure from molecules to solid states are complicated. Therefore, it is a significant challenge to reveal the relationship among molecular structures to the complex microstructure and finally to device functions. This review focuses on the formation, behavior, and evolution of solution-state aggregation of conjugated polymers, which can influence and even determine the solid-state morphology and microstructure, ultimately clarifying the relationship between the microstructure and the properties of conjugated polymers. The critical role of solution-state aggregation is highlighted from a theoretical understanding of molecular interactions between polymer chains (conjugated backbones and/or flexible side chains) and solvent molecules. We highlight the recent progress on high-performance polymer-based devices through the solution-state ag-gregation strategy. Furthermore, we summarize the challenges and essential research direction on the solution-state aggregation, which will be addressed and established in the future. Therefore, an in-depth understanding of polymer aggregation will advance the development of high-performance conjugated polymers in various functional devices. (c) 2022 Elsevier B.V. All rights reserved.